Objective: At the Centre for Contraception, Sexuality and Abortion Leiden, abortion procedures are performed under deep sedation using propofol. Patient's monitoring is performed by nurses qualified in patient sedation management, using pulse oximetry and their clinical judgement. The aim of this study is to examine the effectiveness of capnography in early detection of alveolar hypoventilation during deep sedation in comparison to standard monitoring with pulse oximetry in abortion procedures.